1 // 2 // Copyright (C) 2009 The Android Open Source Project 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 #ifndef UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_ 18 #define UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_ 19 20 #include <openssl/sha.h> 21 #include <unistd.h> 22 23 #include <string> 24 #include <vector> 25 26 #include <base/logging.h> 27 #include <base/macros.h> 28 #include <brillo/secure_blob.h> 29 30 // This class provides a simple wrapper around OpenSSL providing a hash of data 31 // passed in. 32 // The methods of this class must be called in a very specific order: First the 33 // ctor (of course), then 0 or more calls to Update(), then Finalize(), then 0 34 // or more calls to raw_hash(). 35 36 namespace chromeos_update_engine { 37 38 class HashCalculator { 39 public: 40 HashCalculator(); 41 42 // Update is called with all of the data that should be hashed in order. 43 // Update will read |length| bytes of |data|. 44 // Returns true on success. 45 bool Update(const void* data, size_t length); 46 47 // Updates the hash with up to |length| bytes of data from |file|. If |length| 48 // is negative, reads in and updates with the whole file. Returns the number 49 // of bytes that the hash was updated with, or -1 on error. 50 off_t UpdateFile(const std::string& name, off_t length); 51 52 // Call Finalize() when all data has been passed in. This method tells 53 // OpenSSL that no more data will come in. 54 // Returns true on success. 55 bool Finalize(); 56 57 const brillo::Blob& raw_hash() const { 58 DCHECK(!raw_hash_.empty()) << "Call Finalize() first"; 59 return raw_hash_; 60 } 61 62 // Gets the current hash context. Note that the string will contain binary 63 // data (including \0 characters). 64 std::string GetContext() const; 65 66 // Sets the current hash context. |context| must the string returned by a 67 // previous HashCalculator::GetContext method call. Returns true on success, 68 // and false otherwise. 69 bool SetContext(const std::string& context); 70 71 static bool RawHashOfBytes(const void* data, 72 size_t length, 73 brillo::Blob* out_hash); 74 static bool RawHashOfData(const brillo::Blob& data, 75 brillo::Blob* out_hash); 76 static off_t RawHashOfFile(const std::string& name, off_t length, 77 brillo::Blob* out_hash); 78 79 private: 80 // If non-empty, the final raw hash. Will only be set to non-empty when 81 // Finalize is called. 82 brillo::Blob raw_hash_; 83 84 // Init success 85 bool valid_; 86 87 // The hash state used by OpenSSL 88 SHA256_CTX ctx_; 89 DISALLOW_COPY_AND_ASSIGN(HashCalculator); 90 }; 91 92 } // namespace chromeos_update_engine 93 94 #endif // UPDATE_ENGINE_COMMON_HASH_CALCULATOR_H_ 95
